Why do I sometimes see a 'Server is busy' message?

If the server is busy (for example we setup a lot of new accounts at the same time), you may see this message briefly while server load returns to normal levels:

The server is too busy at the moment. Please reload this page few seconds later.

This message can be noticed on peak times only, and only for active servers (active servers are the servers where we add tons of new accounts every day). This message will permanently disappear as soon we will switch new account setups to another server (usually in few days).